1. Field of Use
This invention relates generally to one-piece bimetallic electrical connectors used with electric terminators and to methods for making such connectors.
The connector comprises a copper portion and an aluminum portion joined in a solid state bond and having an axial wire receiving opening in the aluminum portion and having electrical connection means, such as a threaded hole, in the copper portion. Tooling and indexing bosses and tool engaging recess means are integrally formed on the exterior and interior of the aluminum portion.
The method generally comprises the steps of impact extruding an aluminum blank to simultaneously form a neck of reduced diameter, the wire receiving opening and the exterior boss and interior tool engaging recess means to provide a preformed aluminum blank, heat treating the preformed aluminum blank, joining the preformed aluminum blank and a copper blank in a solid state bond by an inertia welding process while employing the external boss and internal tool engaging recess means, and performing subsequent machining steps requiring axial reorientation of the preformed connector while employing the internal tool engaging recess means for indexing purposes.
2. Description of the Prior Art
One-piece bimetallic electrical connectors of various types are used in electrical systems to temporarily or permanently connect an electrical conductor made of one type of metal to another electrical conductor made of a dissimilar metal. U.S. Pat. Nos. 3,876,280 and 3,916,518, which are assigned the same assignee as the present application, disclose one-piece bimetallic electrical connectors and methods for making the same wherein an aluminum portion and a copper portion are joined together entirely across a common interface in a solid state bond effected by a process of inertia welding. The aluminum portion of the connector includes wire connection means in the form of a wire receiving first opening extending axially inwardly from an end face of the aluminum portion of the body and the copper portion of the connector includes connection means in the form of a threaded opening extending inwardly of a side of the copper portion of the body. In the aforementioned patents, the aluminum and copper portions are formed of solid blanks which are welded, and subsequent machining operations are performed to provide the holes therein.
In some one-piece bimetallic connectors of the aforesaid character it is desirable that the copper portion be of smaller diameter than the aluminum portion. However, this poses serious manufacturing problems, especially in the case of relatively small connectors. For example, it is important that the interface between the dissimilar metals be properly located so that a proper solid state bond will result, so that the aluminum portion will not be deformed during the welding process, and so that unnecessary machining operations will not be required in order to remove the welding flash. It is also important that the two sections of dissimilar metals be gripped during the inertia welding process in such a manner and by such means so as to prevent damaging, deforming, or defacing of either of the two portions being joined. It is also important to be able to reorient and accurately position or index the preformed connector about its axis with respect to various machine tools during the final stages of manufacture so that flat surfaces, holes, and threads can be provided in the copper section of the connector, without defacing the exterior of the connector and without causing rupture or collapse of the relatively weak walls surrounding the wire receiving opening in the aluminum portion of the connector. It is also necessary from the standpoint of mass production and cost reduction to carry out the manufacturing steps of the connector in the simplest manner possible and without the need to perform additional machining operations to correct defects introduced at some previous step of manufacture.